Underflip Help

How come every time I try one it always turns into a lincoln but just landing sideways at a 90 degree angle? is there a certain way to lean or pop off the jumo to make you spin more in the air? Help me Please +kk

i drop my left arm down and back almost going for a tail or far back saftey and carve of the lip and it kinda helps my to turn my head a little, so i can still see the landing but it gets my sholders to turn